Auto Invoicing is available in the Customer's billing page at the bottom under Auto Invoicing & Statement Options.
When you select Email Invoices Automatically, the invoice email is sent on the Billing date when the Billing Frequency and the Service Frequency are split; for example, a monthly Service Frequency and a yearly Billing Frequency.
If you have a customer with a Work Order series, and the Billing Frequency is set for Monthly, Quarterly, or Yearly, the Invoice will be emailed on the date you selected.
The invoice is emailed to the email address in the Customer billing page, and to the people who are in the contacts for that Customer billing page with [x] Email Invoices selected.
The existing invoicing For Every Work Order functionality is still the same.
Also watch this video:
Updated, August 2017